Washington: Scientists have for the first time captured images of one of the brightest stars in the infrared sky surrounded by a huge dusty double shell - thanks to the European Southern Observatory’s Very Large Telescope (VLT).
The star and its shells resemble an egg white around a yolky centre, leading the astronomers to nickname the object the ‘Fried Egg Nebula’.
The monster star, known to astronomers as IRAS 17163-3907, has a diameter about a thousand times bigger than our Sun.
At a distance of about 13 000 light-years from Earth, it is the closest yellow hypergiant found to date and new observations show it shines some 500 000 times more brightly than the Sun.
The observations of the star and the discovery of its surrounding shells were made using the VISIR infrared camera on the VLT. The pictures are the first of this object to clearly show the material around it and reveal two almost perfectly spherical shells.
“This object was known to glow brightly in the infrared but, surprisingly, nobody had identified it as a yellow hypergiant before,” said Eric Lagadec (European Southern Observatory), who led the team that produced the new discovery.
Yellow hypergiants are in an extremely volatile phase of their evolution, undergoing a series of explosive events — this star has ejected four times the mass of the Sun in just a few hundred years.
The material flung out during these bursts has formed the extensive double shell of the nebula, which is made of dust rich in silicates and surrounded by gas.
Professor Albert Zijlstra, from The University of Manchester, said: “It is amazing that one of the brightest stars in the infrared sky had previously gone unnoticed. We are seeing a very rare event, when a star is beginning to blow off its outer layers, as a prelude to its final explosion as a supernova.”
The discovery has been published in the journal Astronomy and Astrophysics.
First Published: Wednesday, September 28, 2011, 11:31